Thanks for the responses. You guys have these cars and obviously know what you are talking about.
Based on what you're saying, I think a 92-93 400E is in my future. Economy is only 2 mpg worse, but it's a V8. I love my 280SE 4.5 and know the sinful pleasures of a Mercedes V8.
As for the differences between the 92 and 93, the 92 has a 10:1 compression ratio vs 11:1 for the 93. Is that it? So the 93 has more power, better economy, and a strict requirement for premium only gas.
Very interesting about the decline in quality in 94-95. Plastic oil tubes
. Not just an urban myth then.